window.onload = function () {
    //左侧长度
    var rightHeight = document.getElementsByClassName('right-detail')[0];
    var leftHeight = document.getElementsByClassName('left-nav')[0];
    var bodyHeight = document.body.scrollHeight ;
    if(rightHeight.offsetHeight<bodyHeight){
        leftHeight.style.height=bodyHeight -leftHeight.offsetHeight*1.7 + "px" ;
    }else{
        leftHeight.style.height = rightHeight.offsetHeight + 'px' ;
    }
    console.log(document.body.clientHeight||document.documentElement.clientHeight);

};
